1. Field of the Invention
The present invention relates to an apparatus for controlling the pressure of fuel in a fuel supply line for an internal combustion engine, the fuel supply line being provided with a reservoir tank for holding fuel.
2. Description of the Related Art
A diesel engine provided with a reservoir tank arranged on a fuel supply line for supplying a fuel to the engine is known; see, for example, Japanese Unexamined Patent Publication 62-645. A low pressure pump and a high pressure pump are arranged in series on the fuel supply line, and upstream of the reservoir tank. The fuel from a fuel tank is introduced, via the low pressure pump and then the high pressure pump, into the reservoir tank to which fuel pipes to injectors are connected, whereby fuel having a high pressure is accumulated in the reservoir tank and is introduced into cylinders of the engine via the injectors. A pressure sensor is connected to the reservoir tank, for detecting the pressure of the fuel, and a control device responsive to the detected pressure in the reservoir tank is provided for controlling the operation of the high pressure pump to thereby obtain a predetermined constant pressure of the fuel in the reservoir tank.
If the fuel tank becomes empty, a continuation operation of the high pressure pump causes a generation of bubbles of air in the reservoir tank, before the engine is stopped and fuel charged into the fuel tank, and bubbles thus generated in the reservoir tank cannot be quickly removed when the engine is restarted after the completion of the filling of fuel into the fuel tank, and accordingly, a quick increase in the pressure in the reservoir tank cannot be obtained when the engine is started. This is disadvantageous in that it takes a relatively long time to raise the pressure in the reservoir tank, and thus the engine starting operation is prolonged.